The present invention relates to hot-rolling (piercing) of a heated metal billet under utilization of obliquely disposed, driven rolls. The billet is rolled onto and over a mandrel on a mandrel rod, the mandrel piercing the billet for obtaining the tubular configuration.
Processes of the type above employ mandrel and mandrel rods which are to be reused. The pierced tube is stripped off the mandrel and the latter is inspected and, possibly, replaced. It is also known to introduce the rolled tube as soon as possible into a water tank for cooling. This is particularly necessary as the metal tube, as made, is usually red hot following rolling. Moreover, insertion of water is necessary to prevent oxidation of the inner and outer surfaces, for example, of copper tubing.